Table of Contents
Advertisement
Among other functions, the special-purpose hardware provides the following:
o
Bit-plane-generated high-resolution graphics typically producing 320 by 200 non-
interlaced displays and 320 by 400 interlaced displays in 32 colors, and 640 by 200
non-interlaced or 640 by 400 interlaced displays in 16 colors. There is also a special
mode that allows you to have up to 4,096 colors on-screen simultaneously.
o
A custom display coprocessor that allows changes to most of the special-purpose
registers in synchronization with the position of the video beam. This allows such
special effects as mid-screen changes to the color palette, splitting the screen into
multiple horizontal slices, each having different video resolutions and color depths,
beam-synchronized interrupt generation for the 68000, and more. The coprocessor
can trigger many times per screen. It can trigger in the middle of lines, as well as at
the beginning or during the blanking interval. The coprocessor itself can directly
affect most of the registers of the special-purpose hardware, freeing the 68000 for
general-purpose computing tasks.
o
32 system color registers, each of which contains a twelve-bit number as four bits of
RED, four bits of GREEN, and four bits of BLUE intensity information. This
allows a system color palette of 4,096 different choices of color for each register.
Although an RGB monitor provides the best available output for the system graph-
ics, text, and color, the composite video signal has been carefully designed to provide
maximum NTSC compatibility. This signal may be video-taped or fed to a standard
composite video monitor.
o
Eight reusable 16-bit-wide sprites with up to 15 color choices per sprite pixel (when
sprites are paired). A sprite is an easily movable graphics object whose display is
entirely independent of the background {called a playfield)j sprites can be displayed
"over" or "under" this background. A sprite is 16 low-resolution pixels wide and an
arbitrary number of lines tall. After producing the last line of a sprite on the screen,
a sprite DMA (direct memory access) channel may be used to produce yet another
sprite image elsewhere on-screen (with at least one horizontal line between each
reuse of a sprite processor). Thus, you can produce many small sprites by simply
reusing the sprite processors appropriately.
o
Dynamically-controllable inter-object priority, with collision detection. This means
that the system can dynamically control the video priority between the sprite
objects and the bit-plane backgrounds (playfields). You can control which object or
objects appear "on top" at any time.
Additionally, you can use system hardware to detect collisions between objects and
have your program react to such collisions.
Introduction 3
Hide quick links:
Advertisement
Table of Contents
